Automatic musical instrument



Feb. 28, 1928.

1,660,632 C. F. STODDARD AUTOMATIC MUSICAL INSTRUMENT Filed Feb. 1 1925 r 2 Sheets-Sheet 1 3351 abtmm s Charles H fbda/qra.

Feb. 28, 1928.

C. F. STGDDFKRU AUTOMATIC MUSICAL INSTRUMENT Filed Feb. 25

EYS

Patented Feb. 28, 1928.

UNITED STATES PATENT OFFICE.

CHARLES F. STODDARD, OF NEW YORK, N. Y., ASSIGNOR TO AMERICAN PIANO COM- PANY, 0F NEW YORK, N. Y., A CORPORATION OF NEW JERSEY.

AUTOMATIC MUSICAL INSTRUMENT.

Application filed February 19, 1925.

This invention relates to automatic musical instruments, and pertains more particularly to expression controlling means therefor.

It is an object of the present invention to provide apparatus which shall be capable of reproducing automatically with fidelity and accuracy the original manual performances of pianists of ability, this object being at tained in part by an expression controlling apparatus in which the weight of the moving parts is reduced to a minimum in order that more perfect regulation may be secured due to the elimination of inertia. y

Other objects and advantages of the invention will. appear hereinafter.

A preferred embodiment of the invention selected for purposes of illustration is shown inthe accompanying drawings, in which,

Figure 1 a semi-diagraminatic view, certain parts being shown in section to better illustrate the construction and operation.

Figure 2 is a front elevation of the pneumatic stack with regulator attached.

Figure is a section on the line 3 Figure 1.

Referring to the drawings, the striker. or player pnenmatics 1 are provided which may be connected to the sticker or wippen of a usual piano action by any of the usual means ordinarily employed in the art. As will be understood, a sufiicient number of said.- pnenmatics are provided to operate the entire piano action. Each of the pneumatics 1 is connected by a passage 2 to the valve chamber 3 of a secondary valve 4 which may be controlled in the ordinary manner by a primary 'alvc 5 connected to the tracker bar 6 by a duct 7. The secondary valve units 4 and the striker pneuu'iatics 1 may be con veniently mounted on opposite sides of a board 8, which is provided with a series of passages 9 to which the exhaust chamber 10 of the secondary valves are connected through the passages 11. As illustrated, the passa 9 n I be formed diagonally in the board 8 in oruer that the striker pneumatics 1 on one side of the board may be properly offset in the usual manner for connect-ion with the piano action.

Each of the 9 is connected with. a wind chest which may conveniently be divided by the yartition 12 into twov sections Serial No. 10,186.

18 and 1'3, one for the bass and one for the treble section of the piano. This wind chest, together with the passages 9 leading therefrom to the secondary valves, may be referred to as a regulated exhaust chest, since, as will be hereinafter explained, the exhaust therein is regulated to control playing intensities.

As will be understood, the force of the blow communicated to the string by the collapse of a motor pneumatic will depend upon the degree of exhaust maintained in the regulated exhaust chest. That is, if a high degree of exhaust is maintained in said chest, the collapse of the pneumatic when the secondary valve is operated to subject the pneumatic to exhaust will be more rapid than when the degree of exhaust maintained in the chest is less. It will thus be apparent that by varying the degree of exhaust maintained in the regulated exhaust chest. the force of the blows delivered to the strings by the collapse of the motor pneumatics may be varied, and further that by maintaining the degree of exhaust therein substantially constant, the force of the blows delivered to the strings may be maintained substantially constant.

In the present invention means are provided for governing the degree of exhaust maintained in the regulated exhaust chest for the motor pneumatics and for thereby governing the degree of force applied to the strings of the piano.

For the purpose of explaining the general character of this invention, and to exemplify one practical embodiment thereof for controlling the degree of exhaust maintained in the wind chest, the apparatus illustrated in the drawings has been selected in which the chest 15 also mounted on the board 8 is connected by a passage 16 to a suitable source of exhaust 17. Any of the well-known forms of exhaust means may be employed in connection with the present invention. al though it is preferable that one provided with an adjustable regulator or reservoir be used in order that the exhaust may be main tained substantially constant at any desired level.

Means are provided for subjecting the wind chest 13' to the action of the exhaust means to a greater or less extent, as for example, by restricting more or less the communication therebetween. In the specific illustrative embodiment of the apparatus shown in the drawings, this restrictive action is performed by a movable member of very little weight, influenced, as will be hereinafter explained,'by the pneumatic forces to which it is exposed. This movable member is arranged to cooperate with a fixed supporting member which comprises in the present embodiment a plate or screen 20 proranged to have one sidecxposed partly to the high exhaust maintained in the chest 15 and partly to the regulatedexhaust maintamed in the chest13. As shown, the diaphragm 22 extends over the plate or screen 20 in position to cooperate therewith to control the passage of air -.therethrough from the chest 13 to the chest 15, thus forming in efiect a valve controlling the. flow of air from the action wind chest to the source of exhaust. 7 7 Means are provided to act upon the movable member, herein the diagram 22, in such manner as to increase the efi'ect of high exhaust upon regulated exhaust, as for example, to tend to peel the diaphragm away from the screen or plate 20 to thereby increase the efiective opening between the chests. The said means herein include a chamber 25 to which one side of the diaphragm isrexposed and means to maintain in said chamber a certain degree of exhaust, which for the present may be assumed to be constant, although as will appear later, this degree of, exhaust may be changed for the purpose of securing expression variations. In the specific embodiment of'the invention illustrated, the chamber 25 is connected through an adjustably restricted passage 26 to high exhaust and is also provided with an adjustable vent to atmosphere which will be described in detail hereinafter. readily be understood, any desired degree of exhaust less than high exhaust may be maintained in the chamber 25 hy the relative adjustment of thesizes of the passage 26 to high exhaust and the vent to atmosphere and preferably said degree of exhaust in chamber 25 is maintained at a higher level than the desired degree of regulated exhaust in chest 13, the precise'degree maintained dependingupon the particular design and arrangement of the parts. The chamber 25 maybe referred to as the controlled exhaust chest and hereinis connected to the passage 16 containing high exhaust by means of the I passage 26 having a thumb screw 27 interposed therein which maybe adjusted to con- As. will strict the passage to any desired degree. The chamber 25 also has opening thereto a duct 28 which, as will be shown hereinafter, communicates with atmosphere through adjustable ports of varying sizes.

The difierential between high exhaust in chest-15 and controlled exhaust in chest 25 acting on that part of the diaphragm exposed to high exhaust will exert an upward pull tending to pull the diaphragm against the screen 20 to thereby close certain perforations of the screen to prevent the passage of air therethrough and to restrict communication between the high and regulated .exhaust chests. On the other hand, the differential beteween regulated exhaust in chest 13 and controlled exhaust in chest 25 acting upon that part of the diaphragm exa downward direction. As will be apparent, 7

this downward force will tend to peel a portion of the diaphragm subjected to high exhaust away from the screen 20, thus serving to open additional perforations to permit the passage of air. therethrough. Thus the area of the diaphragm exposed to exhaust may be divided into two portions. That portion which is forced against the screen by the differential of pressures acting thereon may be termed an inactive or dead area and that portion which is drawn away from the screen by the action of'th-e pneumatic forces thereon may be termed an active portion. As will be observed, the active area subjected to high exhaust may vary as the diaphragm is peeled away from the screen orreturne'd' thereto in operation.

Assuming that the forces exerted on' the diaphragm by high exhaust and controlled exhaust remain substantially constant, a condition of equilibrium is established such that regulated exhaust will also be maintained substantially constant, because if, for example, regulated exhaust tends to increase then the downward force of the differential between regulated exhaust and controlled exhaust is decreased and a tendency toward an upward movement'of the diaphragm results." This in turn tends to restrict communication between the high and regulated exhaust chests by closing certain of the perforations 21, permitting regulated exhaust to decrease by the influx of air until thecondition of equilibrium is restored. On the other hand, if regulated exhaust tends to decrease, then the differential between regulated exhaust and controlled exhausttends to increase with the result that there is a tendency toward a downward movement of the diaphragm to open additional perforations 21 'to thereby increase the effective 1 opening between the high and regulated exhaust chests, thus permitting additional air to be withdrawn from the regulated exhaust chest to thereby increase the degree of exhaust maintained therein until the condition of equilibrium is restored. Thus there is a constant tendency on the part of the diaphragm to maintain a position such that the balanced condition shall always prevail.

In the ordinary operation of the piano, several factors act separately or may eom bi-ne tending to cause variations in regulated exhaust. F or example, there may be a more or less constant leakage of atmospheric air to the regulated exhaustchest, which, even though slight, tends to reduce regulated exhaust. By the action just described, however, this would result in a movement of the diaphragm sufiicient to permit a corresponding leakage to the high exhaust chest through the openings 21, thus permitting regulated exhaust to remain substantially constant.

As a further example, in the normal operation of the piano by the motor pneumatics 1 under control of the usual note sheet, each of the motor pneumatics before collapse is filled with air at atmospheric pressure. Immediately that the valve 4: is operated to collapse the pneumatic 1 there is an inrush of atmospheric air into the wind chest past the valve as it travels from one seat to another, followed immediately by the air that is withdrawn from the pneumatic as it collapses.

Due to the action just described, whenever such an inrush of air occurs, the force of regulated exhaust acting upwardly on the diaphragm thereby tends to decrease thus permitting the diaphragm to be peeled away I from the plate 20 to thereby open additional perforations 21 to permit a corresponding quantity of air to be withdrawn to the high exhaust chest. Consequently, there is a tendency to increase regulated exhaust until a condition of equilibrium is again reached.

Such action may take place so promptly and quickly, that, in effect, the action is to maintain the degree of exhaust in the regulated exhaust chest substantially constant, or, in other words, the practical effect is that of maintaining rather than correcting, and this capacity of the apparatus to maintain a constant degree of regulated exhaust rather than to correct changes in regulated exhaust is increased over prior art structures having a similar capacity due to the fact that the diaphragm 22 is substantially withoutinertia. In other words, such action as occurs results almost wholly from the action of juxtaposed pneumatic forces upon each other, and there is no lag or overthrow such as would otherwise occur with parts having substantial weight.

This capacity of the apparatus to maintain a constant degree of regulated exnaust is also increased over prior structures due to the construction and arrangement of the parts whereby the regulator is placed in close proximity to the player pneumatics. Due to this provision the waves of pressure or change of n'essure have a. less distance to travel than in prior art structures in which the regulator and action wind chest have been arranged as so nrate units connected by suitable conduits or wind trunks and consequently an increase in the speed of the regulatinp action is noted. It will also be observed that in the embodiment of the invention illustrated herein the regulator extends for a sul'istantial distance along the bottom of the wind chest and thereby provides direct communication between the regulator and the most frequently used player pneumatic-s in the middle range of the instrument.

Thus, in the playing of a single note there may be several contributing factors tending to reduce regulated exhaust below its normal level which, it not compensated for, might reduce the force with which the blow is struck. .s has been explained, however, the restoring action operates so quickly due to the absence of inertia that in practical cli ect regulated exhaust is maintained substantially constant.

Obviously, in the operation of a piano the number of motor pneumatics operated during the playing of a musical composition varies widely "from time to time. As will be apparent, however, due to the action just described, the degree of exhaust maintained in the regulated exhaust chest and the wind chest will tend to remain substantially constat no matter how many motor meumalics are operated at any given time and the etfective opening between the high and regulated exhaust chests will be automatically varied to permit the eiiectual removal of the air admitted to the regulated exhaust chest.

Thus far it has been assumed that the degree of exhaust maintained in the controlled exhaust chest 17 remains substantially constant, and that it thus exerts a substantially constant dowi'iward pull on the diaphragm. That is, the device thus far has been considered purely a a regulator. Means are provided, however, for changing the degree oi. exhaust maintained in the controlled exhaust chest to thereby change the degree of exhaust maintained in the regulated exhaust chest.

Before passing to a consideration of the specific means employed to accomplish this purpose, it may be convenient to consider the etl'ect of a change in controlled exhaust on the operation of the apparatu and particularly on regulated exhaust. As has been explained, regulated exhaust and high exhaust exert an upward pull on the diaphragm, while controlled exhaust exerts an opposed downward pull thereon. Consequently, assuming that high exhaust remains substantially constant, an increase in controlled exhaust must result in an increase in regulated exhaust in order that the condition of equilibrium may be maintained. -That is, having increased the force acting downwardly on the diaphram,

the force actin uiwardl must also increase in order to maintain the condition of equilibrium. As a specific example of what may occur under these conditions, if controlled exhaust is increased, there first results a tendency to peel the diaphragn i 22 away from the plate thus opening additional perforations to permit a larger quantity of air to be withdrawn'from the regulated exhaust chest whereby the exhaust therein is increased. This increase in turn exerts an increased upward pull on the diaphragm tending to return it somewhat toward the plate to restore a condition of equilibrium at the higher levelof regulated exhaust. is like manner any other change in controlled exhaust will cause a, corresponding chan e in regulated exhaust and in the degree of power applied to t trolled exhaust chest 25 depends on the rela tive sizes of the separate vents leading from this chamber to high exhaust and to atmosphere. Obviously, if the size of the vent to high exhaust is changed by adjustment of the screw 27 while the vent to atmosphere remains unchanged, controlled exhaust will be changed. Equally obviously, if the size of the vent to high exhaust remains unchanged and the size of the vent to atmosphere is changed the degree of controlled exhaust will be changed. In the present embodiment the adjusting screw 27 is designed to be used as a semi-permanent adjusting member by which the instrument may be conditioned to play with a satisfactory range of tone intensities. Means are provided, in addition, for varying the size of the vent to atmosphere in order that controlled exhaust and hence regulated exhaust may be varied to thereby obtain expression variations in play- For this purpose the passage 28 is connected to the chamber 29 formed in the block 30 Communication between the chamber 29 and the chamber 31 is had through a passage 32 formedfin the threaded collar 33 mounted in the partition 34 separating the 1 two chambers. Arranged to cooperate with one end of the passage 32 is a needle valve 35. By adjusting the collar 33 with respect 'to the valve or by adjusting the valve with respect to the collar, as hereinafter explained, the rate of flow of air through the passage 32 maybe adjusted to any desired degree.

Leading from the'chambe'r 31 is a passage 36 which is connected at its otherend to a chamber 37 to which lead the vents 38, 38

116 strin gs and 38", these vents being of different sizes as shown. Each of the vents is controlled by a diaphragm39, 39 39 in order that the vents may be selectively opened or closed to the admission of atmosphere either singly or in combination. If all of the 'diaphragms are raised to permit atmospheric air to'enter through each of the vents, a total opening of considerable capacity is efiect'ed through which atmospheric air may pass to the chamber 37 and thence through the passage 36 into the chamber 31 and thence through the passage 32 to the chamber 29 and thence through the passage 28 to the controlled exhaust chest 25, thus resulting in a decrease in controlled exhaust and a corresponding decrease in'regulated exhaust. If all ofthe vents 38, 33 and 33 are closed to prevent the passage of air therethrough, a higher degree of exhaust will be maintained in the controlled exhaust chest and regulated exhaust chest. By controlling the diaphragms 39, 39 and 39" covering the vents several distinct degrees of exhaust may be established in the controlled exhaust chest 25 to thereby establishirelated distinct degrees of exhaust in the-regulated exhaust chest 13. For instance, each of the diaphragms 39, 396" and 39 may be raised separately or the dia phragms 39, 39 may be opened together while the diaphragm 39 remains closed or the diaphragms 39 and 39 may be raised while the diaphragm 39 remains closed'or the diaphragms 39 and 39 may be raised while the diaphragm 39 remains closed or all oi the diaphragms may be opened or closed together. In each case a different degree of exhaust may be established in the controlled exhaust chest due to the difference in size of the vents and corresponding different degrees of exhaust would be established in the regulated exhaust chest.

It is to be understood, however, that whatever the degree of exhaust established. by

the operation of the diaphragms in the controlled exhau'st chest, a new condition of equilibrium is thereby set up and the new degree of exhaust established in the regulated exhaust chest will beinamtaiued substantially constant by the regulating action of the diaphra m 22 before described. The

diaphragms 39, 39 39 are normally urged to close their respective vents by the springs 40, 40 and 40'. Means are provided, however, for raising the diaphragms against the tension of the springs to open the vents and means are also preferably provided for controlling. such means automatically from the tracker bar. Forthis purpose each of the diaphragms 39, 39 and 39 is provided with a diaphragm chamber 41, 41 and 41* from each of which leads the ducts 42, 422

and 42* which are conuected'to a series of three valve actions, each'ot' which controls one of the diaphragms, Since each of these controlling valve actions is of the same construction, only one will be described in detail herein.

The duct 42 connects the chamber 41 with a valve chamber 43 which is controlled by a duplex valve 44 arranged to control a port 45 to atmosphere and a port 46 leading to the exhaust chest 47 connected to the high exhaust chest 48 by means of the passage 49. The high exhaust chest 48 is con nected to the wind trunk by means of the duct 50. The valve 44 is controlled and operated by a diaphragm 51 covering the diaphragm chamber 52 into which opens the duct 53 leading to the tracker bar 6. lVhen the tracker bar vent 54 controlling the admission of atmosphere to the duct is opened the difierential of pressure between the diaphragm chamber 52 and the exhaust chest 47 causes the valve 44 to be raised to close the port 46 to thereby cut off exhaust from the chamber 41 and to open the port 45 to thereby admit atmospheric air to the chamber 41. Thus under normal conditions with the tracker vent 54 closed and the valve 44 lowered, the chamber 41 is maintained under exhaust from the exhaust chest 47 and when the valve 44 is raised atmospheric air is admitted to the chamber 41 and exhaust YVhen the valve 44 is once raised by venting the tracker duct 53, the valve preferably remains in raised position even though the tracker vent may be immediately closed. In the specific apparatus illustrated this results from the fact that once the valve 44 is opened to admit atmosphere to the valve chamber 41, said valve 44 is held in that position by atmosphere admitted past the valve 44 into a duct 61 from which it passes through a bleeder vent 62 through the duct 63 which communicates with the diaphragm chamber 52. Thus, so long as atmosphere is admitted through the duct 61 the diaphragm 51 will remain lifted and atmosphere will continue to be admitted to the chamber 41.

From the preceding discussion it will appear that small perforations in a note sheet controlling the tracker vent 54, 54 and 5'4" may be employed which may be immediately closed if desired. lVhen used with the illustrative apparatus, each such perforation has the effect of introducing atmosphere to one of the chambers 41, 41 and 41 and even atter the tracker vent is closed atmosphere will continue in the corresponding chamber until purposely exhausted at any subsequent time in a manner such as that about to be described.

In the preferred embodiment of the appaatus illustrated in the drawings, a single valve mechanism controlled by a single tracker vent is employed to cooperate with all or any of the three above described valve mechanisms to negative the efiect of opening one or more of the tracker vents 54, 54- and 4' Such valve mechanism is designated in the drawings by 71. This valve mechanism comprises a valve chamber 72 rontrclled by a duplex valve 73 arranged to open the port 74 to atmosphere and to cl so the port 75 to exhaust from the chest Tb connected to the high exhaust chest 48 by means of the duct 77. The valve is operated by a diaphragm 78 mounted over the diaphragm chamber 79 which communicates by means of the duct 80 with a tracker vent 81.

\Yhen the tracker vent 81 is opened by a suitable opening in the note sheet, atmosphere is admitted to the diaphragm chamber '79 and the differential of pressure between the diaphragm chamber and the exhaust chamber 76 causes the valve 73 to be raised to cut off exhaust from the valve chamber 72 and to permit atmospheric air to enter the chamber.

As already stated, the valve 44 is held in raised position by the atmosphere which is admitted to the diaphragm chamber 52 through the ducts 63 and 61. As will be apparent, if communication between these ducts is out off and suction applied to the duct 63, the differential of pressures which caused the valve 44 to be raised would be equalized and the valve 44 would return to its normal position. Means are provided ac cordingly for performing this operation, such means comprising the valve 85 which normally remains in seated position covering the port 86 leading to the exhaust chamber 42. If this valve is raised, communication between the ducts 61 and 63 will be cut off. At the same time the valve chamber 87 will be subjected to exhaust through the port 80 and this exhaust, communicated through the bleed vent 62 and the duct 63 will cause the valve 44 to return to normal position as before described.

The valve 85 is operated by a diaphragm 88 covering the diaphragm chamber 89 which is in communication with the valve chamber 72 before described through the duct 90. Accordingly, when the valve 73 is in its lowered position the diaphragm chamber 89 is subjected to exhaust and the valve 85 remains in lowered position. When the valve '73 raised by the admission of atmospheric air through the tracker vent 81, atmospheric air is also admitted to the diaphragm chamber 89 with the result that the valve 85 is raised and the valve 44 is returned to normal position. In this manner by opening the tracker vent 81 any of the chambers 41, 41 and 41 which have been opened to atmospheric air are again subjected to exhaust.

The operation just described, so far as it concerns the specific illustrative mechanism,

' depends upon bleeding the diaphragm (sham-.

her 52. If the tracker duct 53 be opened through its vent 54 at the time the vent 81 is opened to initiate the bleeding of the diaphragm chamber 52, atmosphere will enter the chamber 52 more rapidly than it can be exhausted therefrom by the described bleeding, and therefore the effect of opening the vent 81 is negatived and under such circumstances the valve 44 will remain in raised position and atmosphere Wlll continue to be admitted tothe chamber 41.

Also, if the tracker vent 54, for instance,

be opened simultaneously With the tracker vent 81, the latter will inaugurate a tendency to bleed the chamber 52 and keep the valve 44 lowered in theposition shown, but the simultaneous opening of the tracker vent 54 will admit atmosphere to the chamber 52 more rapidly than it can be exhausted by t-hebleederand therefore the valve 44 will be liftedin spite of the opening of the appropriate chamber 41,41 and 41 tracker vent 81. c From the above description itwill be un derstood that whether ornot the tracker vent, 81 be opened, the opening of any of the vents 54, 54 and 54 will have its normal and usual effect to admit atmosphere to the This will be true if an'y vent- 54, 54 or 54 be opened with or without simultaneously opening the tracker vent 81.

' condition ofh-elatively high exhaust to one of relatively low'exhaust. in order, that the condition of high exhaust therein maybe immediately relieved. For this purpose means are provided for venting atmospheric air to the regulated exhaust chest and such means are preferably controlled by the automatic valve mechanism which controls the degree of exhaust maintained therein.

In the preferred embodiment illustrated the regulated exhaust chest 13 is provided with a vent 91 to atmosphere, said vent being controlled by the diaphragm 92 mounted on theblock 93. The block 93 is recessed to provide achamber 94 behindthe diaphragm and thechamber 94 is connected by the duct 95 with the duct 42 leading to the diaphragm chamber 4 1 controlling the vent 38. Thus when the duct 42 is subjected to exhaust to raise the diaphragm 39, the duct 95 is liketherefrom.

wise subjected ,to exhaust to raise the dia phragm 92. It Will,theref0re, be apparent that in making any change in regulated exhaust involving the opening of the vent 38 the vent 91 will also be opened to permit the entrance of atmospheric air to the regulated exhaust chest. It will also be apparent that whilethe opening of the vent 91 permits an. inrush ofatmosphcric air to relieve any temporary undesirable condition of exhaust the continued flow of atmospheric air through the vent will not affect the operation of the instrument for the leakage of air will be compensated-by a corresponding leakage past the diaphragm 22 as hereinbefore explained.

' The apparatus thus far described has the capacity of maintaining in the regulated ex: haust chest a substantially constant degree of'exhaust regardless of the number of mo tor pneumatics operated at any given time, and regardless of the varying amounts of air admitted to the regulated exhaust chest Itlikewise has the capacity of varying the degree of exhaust maintained in the regulated exhaust chest by aseries of substantially distinct steps or increments which produce similar distinct steps or increments in the intensity of the notes played by the instrument due to the varying .force of the blows imparted to the strings by the ham mers. As has also been noted, the degree of exhaust established in the regulated exhaust chest will be maintained substantially constant at any of the several degrees at which it may be set by changing the degree of exhaust in the controlled exhaust chest.

Means are also provided for varying the degree of. exhaust maintained in the regulated exhaust chest not only by distinct in:

crements or steps, as has previously been deregulated exhaust by substantially continuby substantially continuous progression just as inv the previous description incremental changes in regulated exhaustwvere obtained by varying controlled exhaust by substantially distinct increments.

The needle valve previously referred to is mounted on the shaft 103, the shaft being adapted to reciprocate through one wall of the block 30 in order that-the valve may be moved back and forth with respect to the cob lar 33 in order that the constriction imposed on the passage of air throughthe passage 32 may be varied. It will be apparent that ifthe valve is moved from left toright with a continuous movement, the degree of con striction imposed thereby will be continuous ly and progressively increased, and con- 105 scribed, but also for varying-the degree of p til? versely it the valve is moved from right to 'left in the same manner, the degree of constriction iin'posed thereby will be continuously and progressively le ed. A spring 107 is attached to the snail 103 to exert a continuous pull toward the left to normally urge the valve in that direction.

Means are provided for urging the valve in the opposite direction and such means are preferably automatically controlled from the tracker bar by a note sheet. For this purpose the pneumatic 105 is provided having a movable leat' 108 which is extended outwardly into engagement with an adjustable button 109 mounted on the shaft 103. An adjustable screw 108 is also provided to serve as a limit stop for the expansion of the pneumatic. Collapse of the pneumatic will urge the valve to the right to further constrictthe opening 32 and expansion of the pneumatic will permit the spring 107 to return the valve to normal position. The duct 111 is in communication with a valve chamber 1133 controlled by an inside valve 11% which controls the port 115 to atmosphere and the port 116 to the exhaust chamber 117 which may be maintained under exhaust by a suitable connection with the source of eX- haust 17. lVhen the valveis in its raised position the port 115 to atmosphere is closed and the port 116 to the exhaust chamber is opened thus permitting the valve chamber 113 and the duct 111 to be subjected to exhaust to thereby initiate a collapsing movement of the pneumatic 105. When the valve 114: is lowered. the port 116 is closed and atmospheric air is permitted to enter through the port 115 and is communicated to the pneumatic 105 through the duct 111 to permit the pneumatic to expand.

Operation of the valve 114- is effected by means of the diaphragm 11S covering the (lit hragm chamber 119 to which atmospheric air may be admitted through the ducts 120. 121 leading to the tracker vent Normally. .theretore. with the tracker vent 122 closed. the valve 114 is lowered and the pneumatic 105 is opened to atmospheric air and remains in an expanded coi'idition. hen the tracker vent is opened the valve 11% is raised and the pneumatic 105 is subjected to exhaust. it being understood that the size of the pneumatic 105 with re spect to the capacity of the ducts is such that the collapse thereof extends over an appreciable period of time. The rate of collapse. however. may be determined and adjusted to any do ired rate by means of the adiustable screw 123 which serves to constric the duct 111.

it trequently desirable in the mechanical rendition 01 musical compositions to produce crescendo and diminuendo effects of difierent speed That is. it may be desirable .to produce a fast crescendo or a slow crescendo or fast or slow dimin-uendo ellects. For this purpose the by-pass is provided controlled by the valve 125 so that the rate of how of air through duct 111 may be controlled by the adjustable screw 126 instead of by the screw 123 previously described. The screw 126 may be adjusted to provide a less degree 01' constriction in the duct 111 than that provided by the screw 125 so that at any time when air being drawn directly tl'nough the duct 111 the rate of flow therein will be controlled by the screw 125 while at any time when the by-pass 121 is opened the rate 0t flow of air through the duct 111 is controlled by the screw 126.

The valve 125 is operated by the diaphragm 127 mounted over the diaphragm chamber 128 and is in elt'ect a secondary valve controlled by the valve 129. The valve 129 is mounted in a valve chamber 130 connected to the diaphragm chamber 128 by duct 131 and controls a port 132 to atmosphere and a port 133 to the exhaust chamber 117. lVhen the valve is raise the port- 132.

to atmosphere is closed and the port 133 to the exhaust chest is opened thus permitting; the diaphragm chamber 128 to be subjected to exhaust to open the valve 125 to permit the flow of air throughthe by-pass 121. Tlhen the valve is lowered the port- 133 is closed and the port 132 to tItD'IOSPllGI'Q is opened thus admittin atmosphere to the diaphragm chamber 128. The valve 125 is caused thereby to close the by-pass 121- due to the dili'erential of pressures between the diaphragm chamber 128 and the by-pass 12-1. The valve 129 operated by the diaphragm 13%. covering the diaphragm chamber which is in communication with the ducts 136 and 137 leadingto the tracker duct 188.

Thus. when the tracker duct 1% is closed the valve 129 remains lowered and operation of the valve 114 by opening oi": the tracker vent 122 under these conditions will cause a relatively slow collapse of the pneumatic 105. Similarly, it the tracker 122 is now closed the valve will drop permitting the pneumatic 105 to ex 'iandslowly.

()n the other hand. it. the valve ll-l: is operated by opening of the tracker 122 while the valve 129 is also operated by opening of the tracker vent 138. the pneumatic 105 will be collapsed more rapidly due to the fact that the by-pass'12 t is opened under these conditions. Similarly it the tracker vent 122 be closed while the tracker vent 138 rcmains open a more rapid spansion of the pneumatic 105 is thereby permitted.

It will be observed that the app-r. us described has a turcc-fold capacity tor con trollingplaying intensitie the tirst place. it performs a reenlatiiu: function. that is. it maintains a sulrn aiitiall'v constant deot ex jiilrted exhaust nan-st in the .r chest and in the wind chest regardless of the loo ' number of notes being sounded. Second, it

provides for changes in the degee of exhaust maintained by the regulator in the regulated exhaust chest and action wind chest by substantially distinct increments to thereby provide incremental changes in playing intensities. -Thirdly, it provides a means by which the degree of exhaust maintained 'inthe regulated exhaust chest may be varied by substantially continuous progression thereby providing crescendo and diminuendo effects.

It willbe noted, moreover, that in each case the capacity of the apparatus to per. form its function is effective through the action of the diaphragm 22 in controlling the passage of air from the regulating exhaust chest 13 to the high exhaust chest 15 through the openings inthe plate or screen 20. The diaphragm has a two-fold function. It acts as a throttle valve to control the flow of air, and, furthermore, it serves as its own actuating means since the surfaces of the diaphragm provide the areas on which the opposed pneumatic forces act in controlling playing intensities. 7.

It will be observed that the active area of the diaphragmsubjected to the differential between high exhaust and controlled exhaust is very small as compared with the area of the diaphragm acted on by the differential between controlled exhaust and regulated exhaust. In other words, the differential between high exhaustand' con trolled exhaustis acting on a very small area and is opposed to and balanced against the differential between controlled exhaust and regulated exhaust acting on a much larger area. As a result it'is necessary to maintain only a very small differential between controlled exhaust and regulated Vex- .haust because even this small differential acting on a large area can successfully 0ppose the larger dilterential acting on asmaller area.

As has been previously pointed'out, the diaphragm 16 is substantially without weight, and, therefore, substantially without inertia. Accordingly, the device is extremely accurate andi delicate in its operation and permits the extremely quick changes in play ing intensities which are so highly desirable in reproducing mechanically the playing of the artist. 7 i

It is to be understood that the invention maybe variously modified and embodied" within the scope of they subjoined claims.

I claim as my invention 1. In an automaticmusical instrument,

having a main" source of pneumatic power 7 and player pneumatics, in combination, a

high exhaust chest having communication with said source of power, a regulated exhaust chest having communication with said player .pneumatics, and means for controlling communication between said chests,

said means including a diaphragm having a variable active area which is exposed to regulated exhaust and acted upon by regulated exhaust for controlling purposes.

2. In an automatic musical having a main source of pneumatic power and player pneumatics, in combination, a

way act to control communication through aid windway. V 4:111 an automaticmusical instrument having a main sourceyof pneumatic power and player actions, a highexliaust chest communicating with saidsouree of power, a regulated exhaust chest communicating with said player action, means forcontrolling communication between said chests includinga perforate elementand a cooperating flexible diaphragm, said diaphragm being urged toward said perforate-element by the exhaust maintainedin both said high and regulated exhaust chests, and means to influence saiddiaphragm'in a direction tend ing to peel the same from one edge of said perforate element to enlarge the effective opening between said chestsl r 5. In an automatic musical instrument having a main source of pneumatic power and player actions, a high exhaust chest communicating with said source of power, a regulated exhaust chest communicating with said player actions, means for controlling communication between said chests including a perforate element and a cooperating flexible diaphragm, said diaphragm being urged toward said perforate element by the exhaust maintained in both said high and GpIii an automatic musical instrument having a main source of pneumaticpower and player actions, ahigh exhaust chest communicating with said source of power,

"a regulated exhaust chest communicating with said player actions, means for controlling communication between sa1d chests including a flexible diaphragm and a co-' operating perforate element, said diaphragm instrument, i

being urged toward said perforate element by the exhaust maintained in both said high and regulated exhaust chests, and pneumatic means exerting a substantially constant pull on said diaphragm tending to peel the same from one edge of said perforate element to enlarge the effective opening between said chests.

7.111 an automatic musical instrument having a main source of pneumatic power and player actions, a high exhaust chest communicating with said source of power, a regulated exhaust chest communicating with said player actions, a controlled exhaust chest having communication with high exhaust and atmosphere through constricted openings, and means for separating said controlled exhaust chest from said regulated and high exhaust chests and for governing communication between said high and regulated exhaust chests including a rigid perforate plate and a flexible imperforate diaphragm cooperating with said plate.

8. In an automatic musical instrument having a main source of exhaust and player pneumatics, in combination, a windchest for said player pneumatics extending across said instrument, and regulator means mounted on said windchest having direct communication therewith along a substantial portion of the length of said windchest.

9. In an automatic musical instrument, having a main source of pneumatic power and player pneumatics, in combination, a high exhaust chest having communication with said source of power, a regulated exhaust chest having communication with said player pneumatics, means for governing communication between said chests, means for controlling said governing means to establish different degrees of exhaust in said regulated exhaust chest, and means operated by said controlling means for venting atmospheric air directly to said regulated exhaust chest.

10. In an automatic musical instrument, having a main source of pneumatic power and player pneumatics, in combination, a high exhaust chest having communication with said source of power, a regulated exhaust chest having communication with said player pneumatics, means for governing communication between said chests, means for controlling said governing means to establish different degrees of exhaust in said regulated exhaust chest, comprising a plurality of valve means, and means operated by one of said. valve means for venting atmospheric air to said regulated exhaust chest.

11. In an automatic musical instrument having a main source of pneumatic power and player pneumatics, in combination, a windway connecting said source of pneumatic power and said player pneumatics, and means to control communication along said windway between said source of pneumatic power and said player pneumatics, including a perforate element and a diaphragm cooperating therewith, said diaphragm being urged toward said perforate element by the exhaust maintained in said windway on both sides of said perforate element.

12. In an automatic musical instrument having a main source of pneumatic power and player pneumatics, in combination, a windway connecting said source of pneumatic power and said player pneumatics, means to control communication along said windway between said source of pneumatic power and said player pneumatics, including a perforate element and a diaphragm cooperating therewith, said diaphragm being urged toward said perforate element by the exhaust maintained in said windway on both sides of said perforate element, and means to urge said diaphragm away from said perforate element.

18. In an automatic musical instrument having a main source of pneumatic power and player neumatics, in combination, a windway connecting said source of pneumatic power and said player pneumatics, means to control communication along said windway between said source of pneumatic power and said player pneumatics, including a perforate element and a diaphragm cooperating therewith, said diaphragm being urged toward said perforate element by the exhaust maintained in said windway on both sides of said perforate element, and means to exert a substantially constant pneumatic force on said diaphragm to urge it in a direction away from said perforate element.

In testimony whereof, I have signed my name to this specification this 13th day of February, 1925.

CHARLES F. STODDARD. 

